cbh2000

Duplicate of #9. Probably better to add priorities to queue internally, but this is a good workaround in the mean time.

If my memory is correct, that's when Swift switched to binary .swiftdeps. There is a utility to convert them back into text, but it's in the Swift source and someone...

Will need to be a delegate-based notification system instead of callbacks, because the lifespan of a background upload/download may exceed that of the app itself.